An easy filter change, which I've done every 6 months for 14 years, turned into a big job. I'm not positive, but I think it was caused by counterfeit filters I got really cheap on eBay. Installing the housing is really easy, exactly as described in the AppliancePartsPros video. Just three screws, and push-on tubing. But after replacing the filter housing, there was no water! I doubted it was the inlet valves, so I replaced the copper tubing to the frig with braided hose, and a new 1/4 turn valve under the sink. Yay! Cold water and ice!
The answers to the tools, time and challenge level below only apply to the filter housing replacement, not the rest of the plumbing work. The "Socket set" is a 1/4" drive set used because my nut drivers were too long for one of the screws.